Tubing for electrical purposes



March 15, 1932.

J. A. KENNEDY TUBING FOR ELECTRICAL PURPOSES Filed May 20, 1929 Patented Mar. 15, 1932 EUNETEE STATES Parent caries JOSEPH A. KENNEDY, 0F PAW'I'UCKET, RHODE ISLAND, ASSIGN'OR T0 ANAGQNDA AND CABLE COMPANY, OF NEW YORK, N. Y A CORPORATION OF TUBING FOR ELECTRICAL PURPOSES Application filed Kay 2% 1929. Serial lilo. 334,511?

also have a pleasing finish and appearance so that when used in posit-ions exposed to view on the car, as to encase the wires leading to the lamps, it will not detract from the beauty of the car as a whole, but will harmonize with the finish and color efiect of the car. In addition it must have the commonly required qualities of electrical conduit such as adequate tensile strength, flexibility to permit bending in curves, and adequate stillness to resist collapse under lateral pressure and such fiattenin or kinking as would obstruct its bore when nt on a curve. 7

In realizing my object, I have produced a tube having all the characteristics above named and including a smooth, lustrous finish on the outer surface. A series prob.-

39 lem in this connection was to determine how to cover and obscure the rugosity of the tube without impairing its strength and fiexibility. The solution of this problem and other characteristics and features in which the invention consists are explained in the following specification in connection with the drawm The sing e figure of the drawing shows a fragment. of a tube embodying the invention and represented partly in a dismembered condition and partly in its finished state.

The foundation, base or body of my new product is a seamless tube a composed of flexible cotton warp strands b and helical weft or filling'strands c of tightly twisted paper or other suitable material having desirable qualities of strength and stiffness constructed and combined by known methods of circular weaving; substantially like the tube shown in the patent to Charles S. Smith No. 1,016,52'2', dated February 6, l9l2, but with possible variations in relative proportions of the elements. lts strands are made water-repellent and stifiened by saturation or impregnation with a suitable substance for that purpose carried in solution or suspension by a volatile liquid vehicle; for example, I prefer to use for that purpose a. hard asphalt dissolved in volatile solvent and thinned to a consistency resembling water, or l may use an emulsion of asphalt in water or other non-solvent. Whatever may be the vehicle and however the waterproofing agent may be associated with the vehicle, the agent is caused to permeate throughout the strands of the fabric and into and among the pores and fibers of such strands. The tube is then dried, preferably in an oven under artificial heat whereby the solvent or liquid vehicle is driven ofi and the residuum of asphalt or the like is dried and baked. This greatly increases the capacity of the tube to resist collapsing while leaving it still sufiiciently flexible for the purposes in view. 7

A tube so made is inevitably rough on the surface, for the filling strandsnecessarilyhave substantial thiclmess, and the warp strands, being bent around the filling strands, form distinct wales or ridges with shallow grooves or valleys between them.

Then in order to cover this roughness and provide a relatively smooth surface as a ground for the outer finishing compound, 1 wrap the tube a with a number of fine strands d of cotton yarn or equivalent material, laid side by side and wound in parallel helicw with a pitch opposite to that of the helical weft strands. These strands are laid under such tension that they bridge across the grooves or valleys of the tube structure and are so fine and laid so closely together that they form virtually a smooth surface, or at least so nearly approach a smooth surface that the finished surface coating which is afterward laid on them is almost perfectly smooth The threads or strands d are impregnated with a compound of the same nature as that with which the body tube is impregnated, and dried before This is done in order that they shall not absorb any of the compound from the body tube and so diminish the perfection of saturation and water repellence of thelatter. And it is also important that the wrapping strands be adherently united to the body tube so that they will not be dis laced and tend to roughen the finished sur ace when the tube is bent on a curve. The cement or adhesive material for this purpose must be strong, tough and tenacious and remain firm and non-fluid, after having set, even when subjected to heat considerably above the temperature of the atmosphere. Compositions of several classes may be used, such as stearin pitch, asphalt, gums, glues, etc. A suitable gum to use is Manila gum dissolved in alcohol and containing a small proportion of castor oil to give it flexibility after drying; However, at thepresent time I consider a treatment with emulsified asphalt and stearin pitch best suited for these purposes. To illustrate a suitable shop practice for applying this treatment, I may say that the tube is first treated with melted stearin pitch and drawn to the proper external diameter. Then during the operation of wrapping the outer strands, the tube is passed through a bath of emulsified asphalt. This treatment gives the desired adhesion of the wrapping strands but without making the tube unduly stiff. All excess of each solution is wiped off and the residue allowed to dry or set before the final coating treatment is applied.

Finally, the wrapped tube is externally p coated with oil-resistant and acid-resistant lacquer. I have found suitable for use for this purpose a solution of a cellulose compound, as nitrocellulose, viscose, cellulose acetate, etc. in a suitable solvent. I do not claim any novelty in the lacquer itself, but may use any one of a number of lacquers now on the market which have suificient flexibility to withstand bending and temperature changes without cracking or pulling away from the layer of wrapping yarns. The lacquer solution is applied by passing the tube through a bath and wiping ofi the excess by means of a ring shaped die through which the tube passes. The film left ad hering is allowed to dry and additional films are similarly applied to any desired number, until a coating of the desired thickness is built The lacquer dries with a bright glossy surface, and may be given any desired color by admixture of suitable pi ent or dye. Hence the tubing may be nished with an ornamental quality conforming or harmonizing with the brilliancy and various color schemes of automobiles.

The tubing made according to the principles herein described has great tensile strength due to the numerous longitudinal warp strands; substantial resilient stiffness to resist collapse due to the initial stiffness of the helically arranged filling or weft strands, and the additional stiffness imparted to them by the waterproofing compound with which all the strands are impregnated; and flexibility sufficient to permit bending on a curve. a

It is impervious to penetration and deterioration by oil, gasolene, acid and water; being made so by the outer coating or sheath of acid-, oiland water-resistant lacquer, and by the impregnation of the body tube by the waterproofing compound from which oil and acid are excluded by the outer coating. And it is made additionally resistant to collapse, as well as smooth on the outside by the wrapping of fine yarns d and the lacquer coating.

It should be noted that the conduit of this invention, while particularly suited and desirable for use in and about automobiles, is not limited to such use but is adapted to contain and protect insulated wires in other situations as well; and that the naming of specific substances and compounds is not necessarily a limitation to such compounds, et c., otherwise than as indicated by the claims.

\Vhat I claim and desire to secure by Letters Patent is:

1. Tubing for electrical purposes comprising a seamless woven body tube having interwoven longitudinal warps and helical filling, a wrapping of fine yarns wound helically with pitch of opposite inclination to the filling, and an outer layer of lacquer on said wrap- 2. Tubing for electrical purposes comprising a seamless woven body tube having interwoven longitudinal warps and helical filling, a Wrapping of strands finer than the filling laid side by side and wound helically with opposite inclination to the filling so as to bridge across the external wales of the tube and being adherently secured thereto, and an outer layer or sheath of flexible cellulosic lacquer.

3. Electrical conduit having resilient strength resistant to collapse and being flexible and resistant to penetration and deterioration by water, oil and acid, comprising a woven body tube having continuous helical weft strands of twisted paper and being impregnated with a stiffening water-repellent material, a wrapping consisting of a number of fine yarns impregnated with the same composition and being laid side by side and wrapped helically about the body tube with a pitch or inclination opposite to that of the said weft strands, crossing the helical ridges of the body tube and being adhesively bonded thereto, and an outer coat or sheath of cellulosic lacquer deposited on and enveloping said wrapping. I

4. Electrical conduit consisting of a body tube made of interwoven longitudinal warp strands and helical weft strands, saturated signature.

JOSEPH A. KENNEDY. 

